Turbochargers are typically used to increase the power output of an internal combustion engine such as in an automobile or other vehicle. A conventional turbocharger includes a turbine and a compressor. The turbine is rotatably driven by the exhaust gas from the engine. A shaft connects the turbine to the compressor and thereby rotates the compressor. As the compressor rotates, it compresses air that is then delivered to the engine as intake air. The increase in pressure of the intake air increases the power output of the engine.
Modern turbochargers can be complex devices. In particular, the turbine and/or compressor of a turbocharger can be configured to adjust according to the operating condition of the turbocharger and the engine. For example, a variable nozzle turbine (VNT) typically includes variable vanes that adjust according to such operational parameters as the speed and load of the engine and atmospheric conditions. By adjusting the configuration of the vanes, the turbine and, hence, the turbocharger can be made to perform efficiently throughout a range of operation with the engine. One variable nozzle turbine is described in U.S. Pat. No. 6,679,057, entitled “VARIABLE GEOMETRY TURBOCHARGER,” issued Jan. 20, 2004, which is assigned to the assignee of the present invention. Alternatively, another variable-geometry mechanism such as an adjustable piston can be provided for adjusting the flow path through the turbine.
Testing a turbocharger, or the components of a turbocharger, can be difficult. For example, if a problem is detected with an engine or turbocharger of an automobile, it may be difficult to determine if the problem is a result of a malfunction in the engine or the turbocharger, since the two devices may be somewhat interdependent. Further, even if the turbocharger is removed from the engine, it may be difficult or impossible to verify the proper operation of the turbocharger by making a visual inspection of the turbocharger. For example, it may be difficult or impossible to inspect the operation of the adjustable vanes of the turbine or other dynamic aspects of the turbocharger.
Test equipment is conventionally used during the turbocharger manufacturing process, i.e., “end-of-line” equipment that tests the operation of turbochargers after manufacture. Such test equipment can provide a flow of oil to a number of the turbochargers, provide a high pressure air supply at one or more inlet of each turbocharger, and actuate the vanes of each turbocharger while the pressure drop through each turbocharger is measured. Thus, the test equipment can determine if the vanes and other parts of each turbocharger are properly assembled and operating, e.g., according to the drop in pressure that is measured with the vanes in different positions. A flow of oil is typically also delivered to the turbochargers during testing. However, such end-of-line test equipment is typically capable of only static testing. That is, the high pressure air provided at the inlet(s) of the turbocharger does not substantially rotate the turbines or compressors of the turbochargers. Further, the pressure differential(s) across the ports of the turbochargers are measured, but not the rates of flow therethrough.
Thus, there exists a need for an improved system and method for diagnostically testing a rotary flow device such as a turbine or compressor of a turbocharger. The system should be capable of testing aspects of the device with the device adjusted to one or more operational configurations.